Calculates cross section for a electron-Hydrogen impact excitation transition from
the state to the state at energy eb
Type | Intent | Optional | Attributes | Name | ||
---|---|---|---|---|---|---|
real(kind=Float64), | intent(in) | :: | eb | Collision energy [keV] |
Cross Section []
function e_excit_2_3_janev(eb) result(sigma)
!+Calculates cross section for a electron-Hydrogen impact excitation transition from
!+the \(n=2\) state to the \(m=3\) state at energy `eb`
!+
!+###Equation
!+$$ e + H(2) \rightarrow e + H(3) $$
!+
!+###References
!+* Eq. 5 in Ref. 2 [[atomic_tables(module)]]
!+* Section 2.1.1 B in Ref. 2 [[atomic_tables(module)]]
!+
real(Float64), intent(in) :: eb
!+ Collision energy [keV]
real(Float64) :: sigma
!+ Cross Section [\(cm^2\)]
real(Float64), parameter :: sigma0 = 5.984d0
real(Float64), parameter :: deltaE = 1.8888d0
!+ Energy difference between \(n=1\) and \(n=3\):
!+ \(\Delta E = 13.6\left (\frac{1}{2^2} - \frac{1}{3^2}\right )\)
real(Float64), parameter :: alpha = 1.3196d0
!+ Fitting parameter from Section 2.1.1 B in Ref. 2
real(Float64), dimension(5), parameter :: A = [ 38.906d0, 5.2373d0, 119.25d0, &
-595.39d0, 816.71d0]
!+ Fitting parameters from Section 2.1.1 B in Ref. 2
real(Float64) :: ecoll, x, s
ecoll = eb*1.d3
x = ecoll/deltaE
s = A(2) + A(3)/x + A(4)/x**2.0 + A(5)/x**3.0
sigma = 1.d-16 * sigma0/(deltaE*x) * (1.0 - 1.0/x)**alpha * (A(1)*log(x) + s)
if(x.le.1.0) sigma = 0.d0
end function e_excit_2_3_janev